The invention relates to an endoscope of the type referred to in the preamble of Claim 1.
Older endoscope constructions have an image guide, e.g. in the form of a rod lens optical system, between the distally arranged objective and a proximally arranged ocular. Viewing is effected with the eye at the ocular. The endoscope can be rotated at will without viewing being influenced.
Video viewing is becoming increasingly prevalent nowadays. The endoscope is provided with a video camera. Viewing is effected on a monitor, which is installed separately. If the video camera is rigidly connected to the endoscope and if the endoscope is rotated, the image rotates on the monitor which results in considerable irritation of the observer.
Constructions are known in the prior art in which the video camera is arranged proximally on an endoscope with an image guide and is arranged, for instance, freely rotatably hanging there in order to ensure the upright position of the image when the endoscope is rotated. Constructions are also known in which the proximally arranged video camera is rotated with a motor. In order to ensure the upright position of the image, the rotation of the camera can be effected e.g. in dependence on sensors installed in the endoscope which monitor its rotational position and enable control whereby the image is always maintained upright by appropriate rotation of the camera.
In endoscopes of the type referred to above, as are known from U.S. Pat. No. 4,858,001, the video camera is arranged distally directly at the objective in order to economise on an image guide. The problem of rotation of the video camera is solved in this known construction also by a shaft, which carries the video camera and extends through the entire length of the tubular shaft and which is coupled to a rotary actuator in the main body located proximally of the tubular shaft. This construction has, however, disadvantages. The shaft, which extends through the tubular shaft and is connected to a proximal rotary actuator, results in sealing problems. These are very difficult to solve, particularly in the case of medical endoscopes which must be autoclaved in hot steam. If steam enters the endoscope, water condensation on the objective and the video camera results in the endoscope becoming unusable. Furthermore, the shaft takes up a great deal of space in the otherwise free internal cross-section of the tubular shaft, which could be used in other ways.
The object of the present invention resides in providing an endoscope of the type referred to above which may be better sealed and renders a better utilisation of the free cross-sectional area in the tubular shaft possible.
This object is solved in accordance with the invention with the features of Claim 1.
In accordance with the invention, arranged in the free cross-sectional area of the distal tubular shaft section, which remains there after positioning the longitudinally extending devices, particularly such as the conventional light guiding fibre bundle or other devices, such as working passages, flushing passages and the like, proximally of the video camera there is an electric motor which rotates the latter. This structural unit comprising an optical system and a video camera, and optionally includes the motor, which is inherently spatially sealed, can be encapsulated in a vapour-tight manner in order to protect the objective and the video camera from steam, whereby only the signal lines, control lines and power supply lines for the video camera and the motor need pass out to the exterior in a conventional and well understood technique. The free cross-sectional area of the tubular shaft proximally of the electric motor remains free and can be used for other purposes.
The vapour-tight encapsulation is preferably effected with the features of Claim 2. The motor can be disposed outside the inner tube, which encloses only the objective and camera, whereby, however, a sealed rotary bushing would be necessary. The features of Claim 3 are therefore advantageously provided, which results in an encapsulation through which only electric lines pass in a sealed manner.
The inner tube for the vapour-tight encapsulation of the video camera is positioned with a small cross-sectional area in the free cross-sectional area of the tubular shaft. Bushings for electrical lines provided on it must be vapour-tight and cannot be made smaller to an unlimited extent. If the power supply lines for the motor must also pass through them, space problems arise. The features of Claim 4 are therefore advantageously provided. In this construction, the inner tube is made of magnetically permeable material, e.g. high-grade steel and extends through the gap in the motor. The stator thereof is thus located outside the inner tube. With suitable motor constructions an electrical connection is necessary only on the stator which consequently can be positioned outside the inner tube without a special vapour-tight bushing. The inner tube thus requires only bushings for the lines of the video camera. Since the inner tube has a smaller diameter in the vicinity of the motor than at the position of the video camera, the external diameter of the stator of the motor can correspond to the external diameter of the inner tube in the vicinity of the video camera so that it fits into the free cross-sectional area of the tubular shaft section.